Adjustable rotary switch



Feb. 4, 1964 e. H. CORK ETAL ADJUSTABLE ROTARY SWITCH 2 Sheets-Sheet 1 Filed Oct. 26, 1961 7J1]! II 1 11 v I! I! Feb. 4, 1964 G. H. CORK ETAL 3,120,595

ADJUSTABLE ROTARY SWITCH Fiied Oct. 26, 1961 a Sheets-Shed 2 BY 66m 4' PW United States Patent 3,120,595 ADJUSTABLE ROTARY SWITCH Gordon H. Cork, Birmingham, John S. Atkinson, Inkster, and Victor J. Spagnuolo, Birmingham, Mich, assignors to Gernco Electric Co., Detroit, Mich., a corporation of Michigan Filed Oct. 26, 1961, Ser. No. 147,863 6 Claims. (Cl. 200-153) This invention relates to limit switches, and in particular to an adjustable rotary limit switch for actuating one or more sets of electrical contacts, wherein both the time and duration of contact actuation may be selectively varied without the necessity of stopping the apparatus being controlled.

The invention is of particular utility in the controlling of machinery having a repetitive cycle of operation. It is common practice when setting up a job on such a machine to first operate the machine at a slow or set up speed, in order to make certain that the operation is being performed properly. When the machine is brought to operating speed, adjustments in the time sequence of operation are often necessary. With the provision of a device embodying the instant invention, such adjustments may be accomplished while the machine is running, obviating the necessity of repeated stops and starts to arrive at an exact setting for optimum operation. Examples of machines with which such a device may be used to provide this adjustment include punch presses, printing presses, material handling mechanisms, etc.

It is therefore a general object of this invention to provide an adjustable rotary switch for use in conjunction with machinery having a repetitive cycle of operation, which switch is operable to selectively vary the relative timing of steps of the machine operation without stopping the machine.

Another object of the invention is the provision of an adjustable rotary switch operable to selectively control both the point in the cycle at which a given function will occur, and the duration of such occurrence.

A further object is the provision of such a switch in which the cam actuating member of the switch rotates at the same speed as the shaft of the machine to be controlled.

In the prior art, various mechanisms have been ad vanced for actuating limit switches wherein adjusting means are provided to change the point at which such actuation will occur. Most of these mechanisms have been unsatisfactory because adjustment is possible only when the device is idle. The device disclosed in the Kuhn U.S. Patent Number 2,903,528 contributed to the solution of the problem, but nevertheless left some areas dark. One of the disadvantages of a device such as disclosed in Patent 2,903,528 is that the rotary cams which actuate the limit switches rotate a different speed than does the drive shaft of the device. Thus if it is desired to actuate a limit switch upon each rotation of the drive shaft, the cam which actuates the switch must be provided with more than one switch actuating portion.

Another disadvantage of the device disclosed in Patent 2,903,528 is that while the time of limit switch actuation may be adjusted continuously while the device is in motion, the duration of such actuation may not be varied without stopping the device to reposition the actuating cams with respect to one another. concomitantly, to change the duration of switch actuation over a wide range requires the provision of a number of cams having lobes of different arcuate length. To change from a 30 degree actuation to a 300 degree actuation, for example, requires the removal of one set of cams and substitution of another set having suitable actuating lobes.

Therefore it is a particular object of the present in- "ice vention to provide an adjustable rotary switch which overcomes the disadvantages inherent in the prior art as above set forth.

Other objects, advantages and meritorious features will more fully appear from the following specification claims and attached drawings, wherein:

FIG. 1 is a side elevation, partly in cross section, of an adjustable rotary switch embodying the invention;

FIG. 2 is a top elevation of the switch shown in FIG. 1, with the switch cover cut away to show the cam units in detail;

FIG. 3 is a cross sectional View of one of the cam units shown in FIGS. 1 and 2;

FIG. 4 is a side elevation showing the rotary cam of the cam unit of FIG. 3, together with its associated gear; and

FIG. 5 is a side elevation of the adjusting member and differential pinions of the cam unit of FIG. 3.

Referring now to the drawings, FIGS. 1 and 2 show an adjustable switch embodying the invention. The device generally comprises a base 20 and a box-like cover 22. A drive shaft 24 extends the length of the device and is journaled at either end in appropriate bearings (not shown) supported on the base 20.

Contact switches 26 of a suitable conventional design are mounted on the base 2% by means of L-shaped brackets 23. Each bracket 28 is secured to the base 29 by means of screws or the like 30, and the switches are mounted on the brackets by additional screws 32, as shown in FIG. 1. Each switch 26 has a projecting actuating arm 34, with a roller 36 rotatably mounted at the end thereof. It is apparent that the switches may be of any desired type; that is, they may be normally-open or normallyclosed switches, and may be connected in suitable fashion in an electrical circuit via the terminals 33. Furthermore, other devices such as linear transformers, valves, proximity switches or the like could be actuated in lieu of the switches shown in the drawings.

For actuating the contact switches 26 there are provided a plurality of cam units 40, preferably two cam units for each contact switch, as explained more fully hereinafter. As shown in FIGS. 2 and 3, each cam unit 40 comprises a driving gear 42, a driven gear 44, an adjusting member 46, at least one differential pinion 48, and a rotary cam 50. The cam units 40 are all of identical construction, and therefore the description of one of the units applies equally to the rest. It is evident that the number of contact switches 26 and thus the number of cam units to be employed depends entirely upon the particular use to. which the device is to be put. As will more fully appear, the same principle of operation applies whether there is one contact switch or whether there are many contact switches to be actuated.

Referring particularly to FIG. 3, the driving gear 42 is secured to the shaft 24 in any convenient fashion, as by means of a key 52. The driven gear 44 is positioned on the shaft 24 so as to be rotatable relative to the shaft. If desired, the gear 44 may be journaled on the shaft by means of a bearing (not shown). The gear teeth 54 on gear 42 are identical to the gear teeth 56 on gear 44, and therefore upon rotation of shaft 24 through one revolution, gear 42 will rotate with the shaft through one revolution, and gear 44 will be driven by differential pinions 48 through one revolution in the opposite direction. That is, if shaft 24 and gear 42 are rotating in a clockwise direction, gear 44 will be driven counterclockwise, but the revolutions per unit of time of 'gear 42 and gear 44 will be the same under normal conditions of operation.

interposed between gear 42 and gear 44 is an adjusting member or spider 46, which is positioned on the shaft u 24, and is rotatable relative to the shaft, as is gear 44. Member 46 may be likewise journaled on the shaft by means of a bearing (not shown). As shown most clearly in FIG. 5, member 46 has slots 58 cut therein to accommodate the differential pinions 48. The slots 58 are of generally rectangular configuration, as shown. Also, member 46 has radially extending apertures 60 therethrough which intersect the slots 58 at the midpoint of the longer dimension of the slots. Within each of the slots 58 is positioned a differential pinion 48, mounted for rotation on a pin 62 received within aperture 60. The dimensions of member 46 and pinions 48 are such that the teeth of the pinion project beyond the member on either side so as to be in driving engagement with gears 42 and 44 when the unit 40 is assembled on the shaft 24. Thus the rotational axes of pinions 48 is perpendicular to the axis of gears 42 and 44. Various numbers of pinions may be employed but the construction as shown in FIG. 5, utilizing three pinions, has been found to work most satisfactorily.

Mounted on and secured to the driven gear 44 is a rotary cam 50. Preferably, gear 44 has a hub 64 provided with a peripheral groove into which a split retaining ring 66 is snapped to hold cam 50 in place. To hold the cam against rotation relative to gear 44, a post 68 projects from the gear through a suitable aperture in cam 50, as shown in FIG. 3. Each cam unit 40 is prevented from moving axially along shaft 24 by means of a conventional snap ring 67 which encircles the shaft 24 and bears against the hub 64 of gear 44. Referring to FIG. 1, the switch 26 is positioned so that the roller 36 on the switch actuating arm 34 rides along the peripheral edge of cam 50.

Adjusting member 46 has an integral peripheral flange 70, on the outwardly facing edge of which are cut gear teeth to form a worm wheel 72. In driving engagement with the worm wheel 72 is a worm pinion 74, mounted on a shaft 76. A U-shaped supporting bracket 78 is secured to the base 20, and the shaft 76 of the worm pinion is mounted for rotation in suitable apertures in the bracket. The cover 22 is provided with apertures 80 through which the shafts 76 extend. The ends of the shafts projecting through the apertures 80 may be slotted as at 82 so that the worm pinion 74 can be rotated by using a screwdriver or the like. Alternately the projecting portion of the shafts could be knurled, to facilitate adjustment of the pinion by hand. As it is desirable to normally hold the worm pinions 74 stationary, a friction member 84 may be provided which bears against shaft 76'and holds it stationary. It is obvious that this result might be accomplished in any number of ways, and the construction shown at 84 in FIG. 1 is merely for the purpose of illustration.

As shown in FIG. 2, the cam units are arranged on the shaft to operate in pairs, that is, the cams 50 of two such units are positioned closely adjacent each other to actuate one contact switch 26. Each of the pair of earns 50 can be independently adjusted, thus permitting almost infinite variances in both the time and duration of contact switch actuation.

It should be noted that the gears 42, 44 and 48 which comprise the cam driving unit are what is commonly referred to as bevel gears. Admittedly, different types of gears could be utilized, such as modified spur type gears. However, the particular characteristics of bevel gears have been found ideally suited to such an application. Moreover, bevel gears are comparatively easy to manufacture and relatively inexpensive.

As has been stated, the driving gear 42 and the driven gear 44 are identical, and rotate synchronously under normal conditions of operation. Thus gear 44 carrying cam 50 will actuate the contact switch 26 upon each revolution of shaft 24. This makes it possible to construct a cam having one lobe, which may be of any desired arcuate length. With the shaft 24 coupled to the rotating member of the apparatus to be controlled, the cam will rotate synchronously with the rotating member. Thus the operating cycle of the cam and the apparatus to be controlled will be identical. This is a desirable characteristic of such a device, because normally the controlled machine must be actuated during each cycle of its operation, and at the same point during each such cycle.

In the operation of the device embodying the invention, suitable electrical connections are made between the device to be controlled and the terminals 38 of contact switches 26, and the shaft 24 is coupled to the shaft or other rotating part of the controlled apparatus, which will be referred to as the machine in the following description. The discussion will refer to the components of one of the cam units 40, but it is understood that it applies equally to all of the cam units.

As shaft 24 is driven by the rotation of the machine, driving gear 42 rotates therewith, being secured on the shaft as by means of key 52. Adjusting member 46 is normally held stationary by the engagement of its worm wheel 72 with worm pinion 74, and thus differential pinions 4'8 rotate on their axes 62, but do not revolve about shaft 24. Driven gear 44 is in driving engagement with differential pinions 48, and being free to rot-ate with respect to shaft 24, it is driven synchronously with gear 42, but in the opposite direction. Cam 50 is carried by gear 44 and rotates therewith.

Assuming for the moment that a given pair of cams 58-50 that cooperate to actuate one contact switch 26 are positioned in registers with each other. In this situation, the relationship between the various parts would be as shown in FIG. 1. With the cams 50 at the particular point of their cycle as shown in FIG. 1, switch roller 36 is in contact with the trough portion of the cam, and therefore switch 26 is in the normal or unactuated position. As cams 50 are rotated, the roller 36 rides up onto the peak of the cams, and actuating arm 34 is depressed, actuating the switch 26, which remains actuated until the cams rotate to a position where the roller again rides along the cam troughs. With cams similar to that shown in FIG. 1, it is readily apparent that the switch would be actuated during approximately one-half of the cycle, and unactuated for the remainder of the cycle. From the foregoing it can be seen that if only one adjustable cam were used for each contact switch, the duration of cam actuation in each cycle of machine operation could not be controlled without changing cams. No matter what the position of cam 50 in FIG. 1, the duration of switch actuation would of necessity be dependent on the length of the cam peak, if only one cam per switch were employed.

FIG. 4 shows one cam 50 with its associated gear 44, the shaft 24, and also indicates in phantom lines another identical cam 50'. If two such cams each with their associated gears, are placed closely adjacent and used to actuate one switch (see FIG. 2), both the time and duration of switch actuation may be controlled by adjusting one of the cams angularly with respect to the other. For example, if the cam shown in FIG. 4 are rotating in a counter-clockwise direction, the lobe 86 of cam 50 will depress switch arm 34 and activate the switch. The relative angular position of the leading edge of lobe 86 of cam 50 will therefore determine the time of contact switch actuation. As the earns 50 and 50 continue rotation, the roller 34 will be held depressed first by lobe 86 on cam 50, then by both lobe '86 and lobe 88 on cam 50, and finally by lobe 88 alone. The position of the trailing edge of lobe 88 of cam 58' will determine the time of contact switch de-actuation.

Thus the duration of contact switch actuation will be determined by the relative angular position of lobe 86 on cam 50 and lobe 88 on cam 50', as shown in FIG. 4.

With the cam units arranged on the shaft as shown in FIG. 2, the driving gear 42 rotates with the shaft and drives the gear 44 and its cam 50 at the same speed but in the opposite direction of rotation through pinions 48. Adjusting member 46 is held normally stationary by the engagement of its worrn wheel 72 with Worm pinion 74. If it is desired to change the relative angular position of cam 50 with respect to shaft 24 While the device is rotating, the shaft '76 is turned, rotating worm pinion 74, which through worm wheel 72 rotates adjusting member 46 with respect to shaft 24. As gear 42 is fixed with respect to shaft 24, and gear 44 is free to rotate with respect to the shaft, angular displacement of member 46 will cause gear 44 and its cam- 50 to be angularly displaced with respect to the shaft. When two cam units 40 are used to actuate one contact switch, as described hereinabove, each cam may be independently adjusted, both with respect to the shaft 24 and with respect to the remaining earn. With this preferred arrangement, both the time and duration of contact switch actuation may be accurately controlled.

Referring to FIG. 1, the top of the box-like cover 22 is preferably cut away as at 90, and a piece of transparent material 92 placed over the opening so that the cam units may be viewed without removal of cover 22. Each adjusting member 46 is marked with a graduated scale 94 (FIG. 2), and the transparent cover 92 has a hairline (not shown) scribed or otherwise placed thereon vertically in register with the centerline of shaft 24 and cam units 40. With such an arrangement, the operator may selectively adjust each cam 50 a determined number of degrees to achieve the correct cam position. It is apparent that if the driven gear 44 and its cam 50 (FIG. 3) are held sta tionary, one revolution of driving gear 42 will cause the adjusting member to rotate through one-half revolution, the gears 42 and 44 being identical. Thus for every degree of angular movement imparted to adjusting member 46 while the cam unit 40 is in operation, the driven gear 44 and hence cam 50 will be angularly displaced two degrees, or at a ratio of two to one. Therefore the scales 94 on adjusting members 46 must be graduated to indicate 180 degrees as 360 degrees. These scales then are graduated from O to 360 degrees, but extend only 180 degrees around adjusting member 46. This relationship is maintained only for a gear ratio between gears 44 and 42 of one to one. For other ratios, say two to one or three to one, the cam 50 will rotate at a speed different from the speed of shaft 24. As the ratio of shaft speed to cam speed increases, the arcuate length of scale 94 must be decreased, if the contact switch is to be actuated during each shaft revolution, and each cam 50 must have more actuating lobes. For example, if the ratio of shaft speed to cam speed is two to one, the cam must have two lobes, and the scale 94 would extend only 120 degrees graduated as 360 degrees. Thus it is evident that the one to one ratio permits finer adjustment of the cams, and is thus preferable.

If all the cam units are positioned at the zero mark on scales 94 initially, the point at which each switch is to be actuated, and the duration of actuation may be determined, and then each cam 50 may be adjusted so as to effect the desired switch actuation pattern. Thereafter, while the machine is running, if it is found that the sequential timing of operation is not perfect, individual adjustments may be effected on each cam 50 using the procedure outlined hereabove.

What we claim is:

1. In an adjustable rotary switch, the combination comprising: a drive shaft; a rotary member journaled for rotation on said shaft and including a first bevel gear; switch means positioned adjacent said shaft and responsive to the rotation of said rotary member to be actuated thereby; a second bevel gear fixed for rotation on said shaft in aligned confrontation with said first bevel gear; a normally stationary spider journaled on said shaft between said first and second bevel gears, said spider being angularly shiftable with respect to said shaft; at least one differential bevel pinion rotatably mounted on said spider with its axis of rotation extending perpendicularly to the axis of the bevel gears and meshing with such gears to transmit rotation therebetween; means normally adjustably holding said spider against rotation including an adjusting member coupled to said spider to angularly shift the spider and the axis of said differential bevel pinion circumaxially of the drive shaft during rotation of said shaft to thereby angularly reposition said switch actuating rotary member with respect to the shaft.

2. In an adjustable rotary switch, the combination comprising: a drive shaft; a rotary member journaled on the shaft and including a first bevel gear; switch means positioned adjacent said shaft and responsive to the rotation of said member to be actuated thereby; a second bevel gear fixed for rotation on said shaft in aligned eonfrontation with said first bevel gear; a normally stationary spider journaled on said shaft intermediate said first and second bevel gears, said spider being angularly shiftable With respect to said shaft and exihibiting an outwardly facing worm wheel around its periphery; at least one bevel pinion rotatably mounted on said spider with its axis of rotation extending perpendicularly to the axis of the bevel gears and meshing with such gears to transmit rotation therebetween; and a worm pinion meshing with the worm wheel on said spider and including means normally adjustably holding said spider stationary, said worm wheel being rotatable to angularly shift said spider with respect to said shaft while the latter is rotating, with said bevel pinion responsive to the shifting of said spider to angularly position said rotary member with respect to said shaft.

3. In an adjustable rotary switch, the combination comprising: a drive shaft; switch means positioned adjacent said shaft to be actuated upon rotation of the shaft; a pair of cam units adapted to cooperatively actuate said switch means, each of said cam units including: a rotary cam journaled on said shaft and having a first bevel gear, a second bevel gear fixed for rotation on the shaft in aligned confrontation with said first bevel gear, a normally stationary spider journaled on said shaft between said first and second bevel gears and angularly shiftable with respect to said shaft, said spider exhibiting a worm wheel on its periphery, at least one bevel pinion mounted on said spider with its axis of rotation extending perpendicularly to the axis of said bevel gears and meshing with such gears to transmit rotation therebetween, means normally adjustably holding said spider stationary, including a worm pinion meshing with the worm wheel on said spider and rotatable to shift the spider with respect to said shaft during rotation, with said bevel pinion responsive to the shifting of said spider to angularly position said rotary cam with respect to said shaft; said rotary cams being adjacent along said shaft to cooperatively actuate a single switch menas whereby both the time and duration of switch actuation may be selectively varied by the independent adjusting of each of said cams.

4. In an adjustable rotary switch, the combination comprising: a drive shaft; switch means having an actuating arm positioned adjacent the drive shaft; a pair of cam units adapted to cooperatively actuate said switch means, each of said cam units including a rotary cam having a first bevel gear journaled on said drive shaft, a second bevel gear fixed for rotation on said shaft in aligned confrontation with said first bevel gear; a normally stationary spider member journaled on said shaft intermediate said bevel gears and selectively angularly shiftable with respect to the shaft, at least one bevel pinion rotatably mounted on said spider with its axis of rotation extending perpendicularly to the axis of said bevel gears and meshing with such gears to transmit rotation therebetween, means normally adjustably holding said spider stationary during rotation of said gears, including an adjusting member coupled to the spider operable to selectively angularly shift the spider and the axis of the bevel pinion circumaxially about the drive shaft during rotation of said shaft to thereby angularly reposition said rotary cam with respect to said shaft; said rotary cams of said pair of cam units being positioned adjacent each other along said shaft with both rotary cams arranged to contact said switch actuating arm, with each cam having respective peak and trough portions whereby both the time and duration of switch actuation may be controlled by the independent adjusting of each of said cams.

5. In an adjustable rotary switch, the combination comprising: a drive shaft; cam actuable switch means disposed adjacent said drive shaft; a rotary cam journaled for rotation on said shaft to actuate said switch means and including a first bevel gear; a second bevel gear identical with said bevel gear on said cam secured to the shaft for rotation therewith, said first and second bevel gears being disposed in coaxially aligned confronting relations; a normally stationary spider member journaled on the shaft intermediate said first and second bevel gears; at least one bevel pinion rotatably mounted on said spider with its axis of rotation extending perpendicularly to the axis of said bevel gears, said pinion being in driving engagement with the bevel gears to transmit rotary motion therebetween; and an adjusting member connected to said spider and including means normally holding the spider against rotation, said adjusting member being movably operable to angularly shift the spider and the axis of the bevel pinion circumaxially of the drive shaft during rotation of said shaft to thereby vary the relative angular position of said cam with respect to said shaft.

6. In an adjustable rotary switch having a drive shaft; a plurality of cam actuable switch means positioned adjacent said drive shaft, and a plurality of cam units mounted on the drive shaft for actuating said switch means periodically upon rotation of the shaft, there being two identical cam units cooperating to actuate each of such switch means, each of said cam units comprising: a rotary cam having a first bevel gear, said cam journaled on the shaft for rotation; a second bevel gear fixed for rotation on the shaft in aligned confrontation with said first bevel gear; a normally stationary spider journaled on the shaft intermediate said first and second bevel gears and exhibiting on its periphery a worm wheel, said spider being angularly shiftable with respect to said shaft; at least one differential bevel pinion rotatably mounted on said spider with its axis of rotation disposed perpendicularly to the axis of said first and second bevel gears and in driving engagement therewith; means normally adjustably holding said spider against rotation including a worm wheel meshing with the worm wheel on said spider and rotatable to angularly shift the spider with respect to the drive shaft during rotation of the latter, thereby angularly shifting said cam with respect to said shaft through said differential pinion.

References Cited in the file of this patent UNITED STATES PATENTS 2,820,859 Davies et al Jan. 21, 1958 

1. IN AN ADJUSTABLE ROTARY SWITCH, THE COMBINATION COMPRISING: A DRIVE SHAFT; A ROTARY MEMBER JOURNALED FOR ROTATION ON SAID SHAFT AND INCLUDING A FIRST BEVEL GEAR; SWITCH MEANS POSITIONED ADJACENT SAID SHAFT AND RESPONSIVE TO THE ROTATION OF SAID ROTARY MEMBER TO BE ACTUATED THEREBY; A SECOND BEVEL GEAR FIXED FOR ROTATION ON SAID SHAFT IN ALIGNED CONFRONTATION WITH SAID FIRST BEVEL GEAR; A NORMALLY STATIONARY SPIDER JOURNALED ON SAID SHAFT BETWEEN SAID FIRST AND SECOND BEVEL GEARS, SAID SPIDER BEING ANGULARLY SHIFTABLE WITH RESPECT TO SAID SHAFT; AT LEAST ONE DIFFERENTIAL BEVEL PINION ROTATABLY MOUNTED ON SAID SPIDER WITH ITS AXIS OF ROTATION EXTENDING PERPENDICULARLY TO THE AXIS OF THE BEVEL GEARS AND MESHING WITH SUCH GEARS TO TRANSMIT ROTATION THEREBETWEEN; MEANS NORMALLY ADJUSTABLY HOLDING SAID SPIDER AGAINST ROTATION INCLUDING AN ADJUSTING MEMBER COUPLED TO SAID SPIDER TO ANGULARLY SHIFT THE SPIDER AND THE AXIS OF SAID DIFFERENTIAL BEVEL PINION CIRCUMAXIALLY OF THE DRIVE SHAFT DURING ROTATION OF SAID SHAFT TO THEREBY ANGULARLY REPOSITION SAID SWITCH ACTUATING ROTARY MEMBER WITH RESPECT TO THE SHAFT. 